446 V. THE NATURE OF EVOLUTION 



be developed so elaborately that evolution is sometimes possible even 

 without any natural selection. 



The principle of adaptation may exist in the nature of protein 

 itself. Protein molecules are usually inclined to be coagulated by 

 agents which appear to be injurious to organisms, in the coagulation 

 polar groups being folded and lost, while the injurious agents presu- 

 mably can act upon the protein by combining with it through certain 

 polar groups of the protein, and therefore the disappearance of the 

 polar groups can be regarded as the adaptation of the protein not to 

 be further combined by the agents or to reject the agents. 



On the other hand, when the environmental factor is not injurious, 

 the protein adapts itself to the new environment in rearranging its 

 structure to become stable under the environment. And, if affected by 

 some chemical agents possessing certain structures which are not in- 

 jurious, the polar groups of the protein may be rearranged instead of 

 being folded in response to the structural arrangement of the agent, 

 thus the protein becoming able to combine more easily with the latter 

 with the establishment of adaptation to utilize the agent. The trans- 

 mission to genes of such structural changes occurring in the protoplsm 

 protein may result in the adaptation of cells to environmental factors. 



The adaptive change thus raised in local somatic cells can be 

 transferred to the germinal by both virus-like agents and hormones. 

 If the changed structure is liberated in the form of protoplasm par- 

 ticles or virus-like forms, the structure can be precisely transferred to 

 the geminal cells. On the other hand, if the changed structure is 

 released in the form of a certain hormone or a hormone-like agent 

 corresponding to the structure, some influence related to the structure 

 will be exerted on the germ cells through the agent. In higher organ- 

 isms, the environment appears to exert usually its effect on hormonal 

 systems, whereas it is known that hormones have great influences 

 upon the character of organisms. 



In the transmission of a precise structure of somatic cells to ger- 

 minal, a virus-like agent is involved whilst hormones may act as 

 carriers of inexact structures. 



The continued effect of a certain environmental factor on germ 

 cells may cause a fixed change in the genes of the germ cells, with 

 the result that the original structure of the genes is forgotten, thereby 

 the acquired character becoming inheritable. 



In like manner, structure corresponding to the character resulting 



